1. Technical Field
The invention relates to a micro-electro-mechanical system (MEMS) device, a liquid ejecting head, and a liquid ejecting apparatus for use for ejecting a liquid. Particularly, the invention relates to a MEMS device, a liquid ejecting head, and a liquid ejecting apparatus that each include a stacked structural body in which a first electrode layer, a dielectric layer, and a second electrode layer are sequentially stacked.
2. Related Art
MEMS devices that have a stacked structural body in which a first electrode layer, a dielectric layer, and a second electrode layer are sequentially stacked are applied in various apparatuses (e.g., liquid ejecting apparatuses, sensors, etc.). For example, a liquid ejecting head that is a kind of MEMS device is provided with a piezoelectric element that is a kind of the foregoing stacked structural body, a nozzle that ejects a liquid, a pressure chamber that communicates with the nozzle, etc. The liquid ejecting apparatuses in which a liquid ejecting head as described above is mounted include, for example, image recording apparatuses, such as ink jet type printers and ink jet type plotters. Lately, liquid ejecting apparatuses are also applied to various production apparatuses, utilizing their advantages of being capable of causing small amounts of liquid to accurately land on predetermined positions. Examples of the applications include display production apparatuses that produce color filters for liquid crystal displays and the like, electrode forming apparatuses that form electrodes for organic electroluminescence (EL) displays, field emission displays (FED), etc., and chip production apparatuses that produce biochips (biochemical devices). A recording head for an image recording apparatus ejects liquid-state inks and a color material ejecting head for a display production apparatus ejects solutions of various color materials of red (R), green (G), blue (B), etc. Furthermore, an electrode material ejecting head for an electrode forming apparatus ejects an electrode material in a liquid state and a bioorganic material ejecting head for a chip production apparatus ejects a solution of a bioorganic material.
In liquid ejecting heads as mentioned above, a piezoelectric layer that is a kind of a dielectric layer sandwiched between a first electrode layer and a second electrode layer is driven by applying voltage (electric signal) to the two electrode layers. This driving causes pressure changes to occur in the liquid in a pressure chamber and the pressure changers are utilized to eject the liquid from the nozzle. That is, the two electrode layers and the portion sandwiched therebetween function as a piezoelectric element that causes pressure changes in the pressure chamber. Some such liquid ejecting heads have a structure in which a third electrode connected to a wiring substrate or the like is stacked on an end portion of the second electrode layer stacked above a piezoelectric layer and in which the piezoelectric layer and the first electrode layer extend more to an outer side (a side opposite to a drive region) than the third electrode layer does (see JP-A-2004-136663).
In constructions as described above there is a possibility that an end portion of a region where an electric field is formed between the two electrodes, that is, a dielectric layer in an end portion of the second electrode layer, may be broken by leakage current flowing in the end portion of the second electrode. Concretely, there is a possibility that burnout of the end portion of the second electrode layer may occur.